<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Flex Header</title>
    <link rel="stylesheet" href="style.css">
  </head>
  <body>
    <div class="header">
      <div class="left-links">
        <ul>
          <li><a href="#">ONE</a></li>
          <li><a href="#">TWO</a></li>
          <li><a href="#">THREE</a></li>
        </ul>
      </div>
      <div class="logo">LOGO</div>
      <div class="right-links">
        <ul>
          <li><a href="#">FOUR</a></li>
          <li><a href="#">FIVE</a></li>
          <li><a href="#">SIX</a></li>
        </ul>
      </div>
    </div>
  </body>
</html>